Abstract: It is pointed that equating the width of wrinkling wave with length of its curve is principalreason why the strengths of flange wrinkling in cupdeep-drawing process are too low in the past, which are deduced by using energy method. With the aid of improving wrinkling strengths, the predictions on both critical wrinkling dimension of blank without blankholder and minimum blankholder pressure to prevent wrinkling under constant load are completely in agreement with both experimental results and experiential date in production. The solution of blankholder pressure may be also used as fist pressure under spring-loaded blankholder. Relative theoretical and experimental formulas from home and abroad are compared and analyzed either by contrast with reality.

Key words: Bending, Cupdeep-drawing, Instability, Wrinkling